They lived normal lives, paid their bills on time, chatted with neighbours, ordered alcohol in bars. They were not intimate with neighbours, but they lived openly.
One man often left his garage door up, leaving the inside visible. After returning a rented car in Pompano Beach, Florida, Mohammed Atta helpfully reminded the company owner that the oil light was on and that it should be checked.
The portraits that are emerging of the 19 hijackers are striking in their ordinariness. Some seven of them were trained pilots, according to the FBI.
Several of the men lived with their families in and around Vero Beach, Florida. Their children attended public schools, and they drove to shopping malls in Plymouth Voyager vans.
They attended various flight schools throughout Florida. One aviation instructor who trained two of the men on a 757 flight simulator recalled that he thought it curious that the men were not interested in take-offs and landings, choosing instead to focus on how to turn a plane.
If the men were associated with Mr Osama bin Laden, the Muslim cleric, reports in Florida indicate that some of them were not terribly devout in their religious observations, becoming well known in several bars. And there are also reports that aside from the hijackers themselves, many of their associates knew of the plan and helped.
Mr John Kap, owner of the Pink Pony and Red Eye Jacks Sports Bar, told the FBI that three Middle Eastern men spent several hundred dollars on drinks and lap dances late on Monday night. "There were a lot of anti-American things said," Mr Kap told the New York Times. "One of the men said, 'Wait until tomorrow, America is going to see bloodshed." The FBI now has their credit card receipts.
The FBI has released the names of the 18 hijackers and they include men holding Saudi and UAE passports. Among them was Abdul Rahman Alomari, a Saudi Arabian pilot who rented a $1,400 house in Vero Beach. He attended Flight Safety Academy, a well respected aviation school, along with two of the other hijackers.
Several of the hijackers' associates are still at large, including Mr Amer Mohammed Kamfar. According to Mr Kamfar's neighbours, he lived with his wife and four children near Mr Alomari. Two weeks ago a van pulled up and the entire family left suddenly. Said one neighbour: "They were very quiet, normal people. From their trash you could see they shopped at Walmart and ate a lot of pizza."
The challenge for the FBI now is to establish their movements, and the reasons behind them, in the last two years. One of them recently left Florida and moved to Virginia. Another rented a car in August and put some 3,000 miles on it, telling the rental agency that he had driven to the west coast.